The invention is utilized in particular in the area of electronically-commutated brushless direct current (DC) motors, but is not limited to DC motors. Motors of this kind can be used in a variety of applications, examples being in automotive engineering, cooling pumps or steering support systems. Other application areas include ventilator fans in power supply units, or spindle motors in disk drives for data processing systems, just to mention a few.
An electronically-commutated, brushless motor basically consists of a shaft, a rotor assembly equipped with one or more permanent magnets arranged on the shaft, and a stator assembly which incorporates a stator core and phase windings. Two bearings are mounted on the shaft at an axial distance to each other for rotatably supporting the rotor assembly and the stator assembly relative to each other.
FIG. 1 shows a schematic circuit diagram of a drive circuit for a three-phase motor. The drive circuit in the illustrated example has six power transistors and additional further electronic components (not shown) which control motor operation. It is known in the prior art to design the motor drive electronics as an complete unit on a printed circuit board which is fitted to the motor as a plug-in unit or by other means. The connection between the PCB and the motor is established via connecting wires and cables which are connected to the PCB by soldering, plugging or similar means. Plug and solder connections as well as the wire lengths between the motor and the PCB increase the electrical resistance of the motor and, consequently, reduce the electrical voltage available at the motor winding terminals.
Connections which can have a negative influence on the electrical resistance of the motor are created inside and outside a motor in the following areas (just to give a few examples): the connection of the motor phase windings with the neutral point (Y connection) in the case of a three-phase motor; the connection of windings belonging to one phase; the connection of the phase windings with a plug fitted to the motor housing or a cable; or the connection between such a plug and the electronics via a further plug connector or via a further solder connection to the electronics.
From an earlier German patent application of the same applicant dated the 22nd of June 2001 (with the reference number 101 30 117.0) it is known in general to connect the endings of phase windings within the motor via lead frames. These lead frames have tracks stamped out of a sheet metal, the tracks being separated from each other by electrically-insulated material. Lead frames can be integrated in a plastic support component. The endings of the phase windings of the motor are connected to the lead frame by soldering, welding or a plug connection. In this application it has been described that signal wires in the motor drive electronics are connected via a plug/socket section. Relays are contained in a plastic support component designed for this purpose. The electronic components for the motor drive device are arranged on their own PCB, this being connected with the aforementioned signal wires. This causes the disadvantage described above resulting in increased resistance caused by plug or solder connections and additional cable wire lengths.
An object of the invention is therefore to provide a device for connecting electronic components in an electronic drive circuit for an electric motor which minimizes losses caused by plug or solder connections and the lengths of cable wires and, in particular, reduces the number of connections and cable wire lengths to a minimum.